Device comprising a combination of a chamber and a piston

ABSTRACT

The object of the invention is to provide a reliable and inexpensive combination of a chamber and a piston to be used in any device where such a combination is needed so that it comply with specific demands towards the operation force for e.g. pumps, specifically manually operated pumps. 
     By a device comprising a chamber and a piston positioned inside the chamber said chamber and said piston relatively movable to each other in a predetermined direction of movement between a first position and a second position of which the cross-section of the chamber in a plane perpendicular to the direction of movement is larger at the first position than at the second position, the change in the cross section of the chamber is essentially continuous between the first position and the second position and the cross-section of the piston in a plane perpendicular to the direction of movement is arranged to adapt itself to the cross-section of the chamber. 
     It is further possible that the piston has a fixed geometrical shape, that the wall of the chamber has different sizes of cross-sections in the direction of the movement and is arranged to adapt itself to the piston. Moreover, both the piston and the and the wall of the chamber can adapt itself to each other.

TECHNICAL FIELD

This invention concerns a device comprising a combination of a chamberand a piston positioned in the chamber, said chamber and said pistonrelatively movable to each other in a predetermined direction ofmovement between a first and a second position. Such combinations can beused in any device where a combination of a chamber and a piston isneeded. Examples of these devices are any kind of piston pumps,specifically manually operated piston pumps, actuators, shock absorbers,motors etc.

BACKGROUND OF THE INVENTION

A problem with existing manually operated piston pumps is that the armsor leg(s) of the user of the pump are loaded directly. The force thatneeds to be applied to operate the pump increases with every stroke, ifthe pressure of a gaseous and/or liquid medium inside a closed body,e.g. a tyre, is to be increased. The force remains the same if themedium is a non-compressable liquid, as e.g. water in water pumps. Thisgives the user a wrong feeling. In the design process the magnitude ofthese forces is often decided as a compromise between the expectedweight and the initiating power of the arms or leg(s) of the user andthe time it takes to pump the body. The diameter of the piston definesthe level of force to be applied to operate the pump. The pumping timeis also defined by the length of the cylinder of the pump. This limitsthe use of the pump to persons of a certain height. Bicycle and carpumps are clear examples. Especially high-pressure pumps are optimizedfor male users (design starting point: 75 kg weight, 1.75 m length)despite the fact that women and teenagers make up the largest group ofracer bike users.

When pressures ranging from 4-13 Bar have to be obtained using the samepump, e.g. a high-pressure bike pump, the combination of low pumpingtime for low-pressure high-volume tyres and low forces for high-pressurelow-volume tyres becomes a problem, if the pump is a hand-operated(floor)pump. If a low-pressure tyre with a relatively large volume hasto be pumped by a high-pressure pump, it takes longer time thannecessary and the user does not feel any reaction forces at all whichgives the user a wrong feeling. It is often difficult to get the righttire pressure of a high pressure tire with e.g. a high pressure floorpump, because often only a part of a last pump stroke is required,mostly not at the end of the stroke. Therefore it is difficult tocontrol the movement and stop of the piston because of a too highoperating force. New types of bicycles and tyres were introduced at thebeginning of the 1980's. These new bicycles are widely used astransportation means. Therefore, universal piston pumps have beenobserved in the patent literature. These pumps can pump bothlow-pressure and high-pressure tyres by means of a reasonable amount offorce and time. This is accomplished through the simultaneouslyapplication of several coaxial/parallel cylinders and pistons that canbe switched on and off (e.g. DE 195 18 242 A1, DE 44 39 830 A1, DE 44 34508 A1, PCT/SE96/00158). These solutions are expensive and sensitivetowards malfunctioning due to the fact that key parts are incorporatedin the pumps several times.

A bicycle floor pump which has from the outside the form of a puresingle truncated cone with a movable piston is known from the earlybicycle literature. The aim is apparently to reduce the operating force,as the cone is standing upside down. There exists apparently no priorart of pistons which can move in a chamber with different diameters andwhich seal properly and tight. This is not surprising because it is notso easy to produce a reliable piston of that kind, specifically not withthe state of the art at that time even when only low pressure highvolume tires existed. A leakage would not cause a problem for such aconsumer product. For current high pressure pumps or those forprofessional purposes it is descisive that no leakage exist. The demandstowards the piston construction for high pressure levels and/or low andhigh pressure levels, causing no leakage are different from those whichsolely has to do with lower pressure levels.

U.S. Pat. No. 5,503,188 concerns an organical constructed pipeline flowstopper with an inflatable impervious bag. This stopper cannot becompared with a moving piston. In a pump can the media to be compressedand/or moved continuously cause a dynamic load on the piston while thewall of the pressurized chamber of the pump can change its cross-sectionregarding area and/or shape perpendicular to the direction of movementof the piston between one point and another which gives specific sealingproblems. These sealing problems are solved by the present invention.

THE OBJECT OF THE INVENTION

The object of the invention is to provide a reliable and inexpensivedevice comprising a combination of a chamber and a piston, to which itsdesign has to comply to specific demands towards the operating force.These devices can be specifically be piston pumps but also devices likeactuators, shock absorbers or motors etc. Manually operated piston pumpswill be comfortable to use by the target group without compromisingpumping time, while devices which are not manually operated will gain asubstantial reduction of investments and operational costs, due to alower operating force. The invention aims to overcome the abovementioned problems.

SUMMARY OF THE INVENTION

In general, a new design for a combination of a chamber and a piston fore.g. a pump must ensure that the force to be applied to operate the pumpduring the entire pumping operation is low enough to be felt as beingcomfortable by the user, that the length of a stroke is suitable,especially for women and teenagers, that the pumping time is notprolonged, and that the pump has a minimum of components reliable andalmost free of maintenance time.

According to the invention, these requirements are fulfilled by means ofthe provisions in the characterization part of claim 1. By a device,comprising a chamber and a piston positioned inside said chamber andsaid piston relatively movable to each other in a predetermineddirection of movement between a first position and a second position ofwhich the cross-section of the chamber in a plane perpendicular to thedirection of movement is larger at the first position than at the secondposition, the change in the cross-section of the chamber is essentiallycontinuous between the first position and the second position and thecross-section of the piston in a plane perpendicular to the direction ofmovement is arranged to adapt itself to the cross-section of thechamber.

According to the invention, these requirements are fulfilled by means ofthe provisions in the characterization part of claim 2. By a devicecomprising a combination of a chamber and a piston positioned inside thechamber, the chamber and the piston relatively movable to each other ina predetermined direction of movement between a first position and asecond position, the cross-section of the piston in a planeperpendicular to the direction of movement is larger at a first pistonposition than at a second piston position, the change of thecross-section of the piston is essentially continuous between the firstpiston position and the second piston position, the cross-section of thechamber in a plane perpendicular to the direction of movement is largerat the first position than at the second position, the change of thecross-section of the chamber is essentially continuous between the firstposition and the second position and the cross-section of the chamber isarranged to adapt itself to the cross-section of the piston.

According to the invention, these requirements are fulfilled by means ofthe provisions in the characterization part of claim 3. By A devicecomprising a combination of a chamber and a piston positioned inside thechamber, said chamber and said piston relatively movable to each otherin a predetermined direction of movement between a first position and asecond position, the cross-section of the piston in a planeperpendicular to the direction of movement is larger at a first pistonposition than at a second piston position, the change of thecross-section of the piston is essentially continuous between the firstpiston position and the second piston position, the cross-section of thechamber in a plane perpendicular to the direction of movement is largerat the first position than at the second position, the change of thecross-section of the chamber is essentially continuous between the firstposition and the second position and a cross-section of the chamber andthe piston, respectively is arranged to adapt itself to thecross-section of the piston and the chamber, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in detail below by means of diagrams anddrawings. The following is shown in the diagrams or drawings—atransversal cross-section means a cross-section perpendicular to themoving direction of the piston and/or the chamber, while thelongitudinal cross-section is the one in the direction of said movingdirection:

FIG. 1 shows a so-called indicator diagram of a one-stage single workingpiston pump with a cylinder and a piston with a fixed diameter.

FIG. 2A shows an indicator diagram of a piston pump according theinvention part A shows the option where the piston is moving, while partB shows the option where the chamber is moving.

FIG. 2B shows an indicator diagram of a pump according to the inventionwhere the transversal cross-section increases again from a certain pointof the pump stroke, by still increasing pressure.

FIG. 3A shows a longitudinal cross-section of a pump with fixeddifferent areas of transversal cross-sections of the pressurizingchamber and a piston with radially-axially changing dimensions duringthe stroke—the piston arrangement is shown at the beginning and at theend of a pump stroke (first embodiment).

FIG. 3B shows an enlargement of the piston arrangement of FIG. 3A at thebeginning of a stroke.

FIG. 3C shows an enlargement of the piston arrangement of FIG. 3A at theend of a stroke.

FIG. 4A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and a piston with radially/partially axially changing dimensionsduring the stroke—the piston arrangement is shown at the beginning andat the end of the pump stroke (second embodiment).

FIG. 4B shows an enlargement of the piston arrangement of FIG. 4A at thebeginning of a stroke.

FIG. 4C shows an enlargement of the piston arrangement of FIG. 4A at theend of a stroke.

FIG. 4D shows section A-A of FIG. 4B.

FIG. 4E shows section B-B of FIG. 4C.

FIG. 4F shows an alternative solution for the loading portion of FIG.4D.

FIG. 5A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and a piston with radially-axially changing dimensions duringthe stroke—the piston arrangement is shown at the beginning and at theend of the pump stroke (third embodiment).

FIG. 5B shows an enlargement of the piston arrangement of FIG. 5A at thebeginning of a stroke.

FIG. 5C shows an enlargement of the piston arrangement of FIG. 5A at theend of a stroke.

FIG. 5D shows section C-C of FIG. 5A.

FIG. 5E shows section D-D of FIG. 5A.

FIG. 5F shows the pressurizing chamber of FIG. 5A with a piston meanswith sealing means which is made of a composite of materials.

FIG. 5G shows an enlargement of the piston means of FIG. 5F during astroke.

FIG. 5H shows an enlargement of the piston means of FIG. 5F at the endof a stroke, both while it is still under pressure and while it is notanymore under pressure.

FIG. 6A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and a fourth embodiment of the piston with radially-axiallychanging dimensions during the stroke—the piston arrangement is shown atthe beginning and at the end of the pump stroke.

FIG. 6B shows an enlargement of the piston arrangement of FIG. 6A at thebeginning of a stroke.

FIG. 6C shows an enlargement of the piston arrangement of FIG. 6A at theend of a stroke.

FIG. 6D shows the pressurizing chamber of FIG. 6A and a fifth embodimentof the piston with radially-axially changing dimensions during thestroke—the piston arrangement is shown at the beginning and at the endof a pump stroke.

FIG. 6E shows an enlargement of the piston arrangement of FIG. 6D at thebeginning of a stroke.

FIG. 6F shows an enlargement of the piston arrangement of FIG. 6D at theend of a stroke.

FIG. 7A shows a longitudinal cross-section of a pump comprising aconcave portion of the wall of the pressurizing chamber with fixeddimensions and a sixth embodiment of the piston with radially-axiallychanging dimensions during the stroke—the piston arrangement is shown atthe beginning and at the end of the pump stroke.

FIG. 7B shows an enlargement of the piston arrangement of FIG. 5A at thebeginning of a stroke.

FIG. 7C shows an enlargement of the piston arrangement of FIG. 5A at theend of a stroke.

FIG. 7D shows section E-E of FIG. 7B.

FIG. 7E shows section F-F of FIG. 7C.

FIG. 7F shows examples of transversal cross-sections made by FourierSeries Expansions of a pressurizing chamber of which the transversalcross-sectional area decreases, while the circumpherical size remainsconstant.

FIG. 7G shows a variant of the pressurizing chamber of FIG. 7A, whichhas now a longitudinal cross-section with fixed transversalcross-sections which are designed in such a way that the area decreaseswhile the circumference of it approximately remains constant ordecreases in a lower degree during a pump stroke.

FIG. 7H shows transversal cross-section G-G (dotted lines) and H-H ofthe of the longitudinal cross section of FIG. 7G.

FIG. 7I shows transversal cross-section G-G (dotted lines) and I-I ofthe of the longitudinal cross section of FIG. 7H.

FIG. 7J shows a variant of the piston of FIG. 7B, in section H-H of FIG.7H.

FIG. 7K shows other examples of transversal cross-sections made byFourier Series Expansions of a pressurizing chamber of which thetransversal cross-sectional area decreases, while the circumphericalsize remains constant.

FIG. 8A shows a longitudinal cross-section of a pump comprising a convexportion of the wall of the pressurizing chamber with fixed dimensionsand a seventh embodiment of the piston with radially-axially changingdimensions during the stroke—the piston arrangement is shown at thebeginning and at the end of a pump stroke.

FIG. 8B shows an enlargement of the piston arrangement of FIG. 5A at thebeginning of a stroke.

FIG. 8C shows an enlargement of the piston arrangement of FIG. 5A at theend of a stroke.

FIG. 9A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and an eight embodiment of the piston with radially-axiallychanging dimensions during the stroke—the piston arrangement is shown atthe beginning and at the end of a pump stroke.

FIG. 9B shows an enlargement of the piston arrangement of FIG. 9A at thebeginning of a stroke.

FIG. 9C shows an enlargement of the piston arrangement of FIG. 9A at theend of a stroke.

FIG. 9D shows the piston of FIG. 9B with a different tuning arrangement.

FIG. 10A shows a ninth embodiment of the piston similar to the one ofFIG. 9A with fixed different areas of the transversal cross-section ofthe pressurizing chamber.

FIG. 10B shows an enlargement of the piston of FIG. 10A at the beginningof a stroke.

FIG. 10C shows an enlargement of the piston of FIG. 10A at the end of astroke.

FIG. 11A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and an tenth embodiment of the piston with radially-axiallychanging dimensions during the stroke—the piston arrangement is shown atthe beginning and at the end of a pump stroke.

FIG. 11B shows an enlargement of the piston of FIG. 11A at the beginningof a stroke.

FIG. 11C shows an enlargement of the piston of FIG. 11A at the end of astroke.

FIG. 12A shows a longitudinal cross-section of a pump with fixeddifferent areas of the transversal cross-sections of the pressurizingchamber and an eleventh embodiment of the piston with radially-axiallychanging dimensions during the stroke—the piston arrangement is shown atthe beginning and at the end of a pump stroke.

FIG. 12B shows an enlargement of the piston of FIG. 12A at the beginningof a stroke.

FIG. 12C shows an enlargement of the piston of FIG. 12A at the end of astroke.

FIG. 13A shows a longitudinal cross-section of a pump with variabledifferent areas of the transversal cross-section of the pressurizingchamber and a piston with fixed geometrical sizes—the arrangement of thecombination is shown at the beginning and at the end of the pump stroke.

FIG. 13B shows an enlargement of the arrangement of the combination atthe beginning of a pump stroke.

FIG. 13C shows an enlargement of the arrangement of the combinationduring a pump stroke.

FIG. 13D shows an enlargement of the arrangement of the combination atthe end a pump stroke.

FIG. 14 shows a longitudinal cross-section of a pump with variabledifferent areas of the transversal cross-section of the pressurizingchamber and a piston with variable geometrical sizes—the arrangement ofthe combination is shown at the beginning, during and at the end of thepump stroke.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows the so-called indicator diagram. This diagram schematicallyshows the adiabatic relation between the pressure p and the pump strokevolume V of a traditional single-stage one-way working piston pump witha cylinder with a fixed diameter. The increase in the operating force tobe applied per stroke can be read directly from the diagram and isquadratic to the diameter of the cylinder. The pressure p, and thus theoperating force F, increases during the stroke normally until the valveof the body to be inflated has been opened.

FIG. 2A shows the indicator diagram of a piston pump according theinvention. It shows that the diagram for pressure p is similar to thatof traditional pumps, but that the operating force is different anddepends entirely on the chosen area of the transversal cross-section ofthe pressurizing chamber. This depends entirely on the specification,e.g. that the operating force should not exceed a certain maximum. Theshape of the longitudinal and/or transversal cross-section of thepressurizing chamber can be any kind of curve and/or line. It is alsopossible that the transversal cross-section e.g. increases by increasingpressure (FIG. 2B). An example of the operating force is the dashedthick line, 1 or 2. The different wall possibilities marked 1 and 2correspond to the earlier mentioned lines 1,2 of the diagram. TheA-section relates to a pump of which only the piston is moving, whilethe B-section relates to pumps where only the chamber is moving. Acombination of both movements at the same time is also possible.

FIG. 2B shows an example of an indicator diagram of a piston pump thathas a chamber with a transversal cross-section that increases byincreasing pressure.

FIGS. 3A,B,C show details of the first embodiment. The piston moves inthe pressurizing chamber which comprises cylindrical and cone-shapedportions with circular transversal cross-sections with diameters thatdecrease when the pressure of the gaseous and/or liquid media increases.This is based on the specification that the operating force should notexceed a certain maximum. The transition between the various diametersis gradual without discrete steps. This means that the piston can slideeasily in the chamber and adapt itself to the changing areas and/orshapes of the transversal cross-sections without loss of sealingability. If the operating force has to be lowered by increasingpressure, the transversal cross-sectional area of the piston isdecreasing and by that the length of the circumference as well. Thecircumferical length reduction is based on compression up to thebuckling level or by relaxation. The longitudinal cross-section of thepiston means is trapezoid with variable angle α less than e.g. 40° withthe wall of the pressurizing chamber, so that it cannot deflectbackwards. The dimensions of the sealing means change in threedimensions during every stroke. A supporting portion of the pistonmeans, e.g. a disk or integrated ribs in the sealing means, e.g.positioned on the non-pressurized side during a pumping stroke of thepiston protects against deflection under pressure. A loading portion ofthe piston means, e.g. a spring washer with several segments, can alsobe mounted e.g. on the pressurized side of the piston. This squeezes theflexible sealing portion towards the wall. This is expedient if the pumphas not been used for some time and the piston means has been folded forsome time. By moving the piston rod, the sides of the trapezoidcross-section of the sealing portion of the piston means will be pushedaxially and radially, so that the sealing edge of the piston follows thedecreasing diameter of the pressurizing chamber. At the end of thestroke, the bottom of the chamber in the centre has become higher inorder to reduce the volume of the dead room. The piston rod is mainlyguided in the cap which locks the pressurizing chamber. As the piston inboth directions of its movement seals to the wall of the chamber, thepiston rod e.g. comprises an inlet channel with a spring force-operatedvalve, which is closed in case of overpressure in the chamber. Withoutthe use of the loading portion in the piston means, this separate valvewould be superfluous. In the pump design according to the invention, theparts of the pump have been optimized for working forces. The insidediameter of the pump is over the main part of the pump chamber lengthlarger than that of existing pumps. Consequently, the inlet volume ishigher, even though the volume of the remaining part of the chamber islower than that of existing pumps. This ensures that the pump can pumpquicker than existing pumps, while the maximum operating force requiredis significantly reduced and lower than the level reported by consumersto be comfortable. The length of the chamber can be reduced, so that thepump becomes practical, even for women and teenagers. The volume of astroke is still higher than that of existing pumps.

FIG. 3A shows a piston pump with a pressurizing chamber 1 with portionsof different areas of its transversal cross-sections of wall sections2,3,4 and 5. The piston rod 6. The cap 7 stops the piston means andguides the piston rod 6. The transitions 16,17 and 18 between thesection with the walls 2,3,4 and 5. The longitudinal centre axis 19 ofthe chamber 1. The piston 20 at the beginning and 20′ at the end of thepump stroke.

FIG. 3B shows the sealing portion 8 made of an elastic material and theloading portion 9, e.g. a spring washer with segments 9.1, 9.2 and 9.3(other segments not shown) and a support portion 10 of the piston meansattached to the piston rod 6 between two portions of locking means 11.The piston rod 6 has an inlet 12 and a valve 13. The angle α between thesealing portion 8 of the piston means and the wall 2 of the pressurizingchamber 1. The sealing edge 37.

FIG. 3C shows outlet channel 14 in a means 15 which reduces the volumeof the dead room. Angle α₂ between the sealing portion 8′ of the pistonmeans and the wall 5 of the pressurizing chamber 1. The loading portion9′.

FIGS. 4A,B,C,D,E,F show details of the second preferred embodiment. Thesealing portion of the piston means is made of an elastically deformablematerial supported by a support means which can rotate around an axisparallel to the center axis of the chamber. The consequence of thismovement is that it supports a larger area of the sealing means thehigher the pressure is in the chamber. The loading portion for thesupport portion initiates the movement of the support means. The loadingportion in the form of a flat-shaped spring can change dimensions in adirection perpendicular to the centre line of the chamber. The springbecomes more and more stiff the higher the pressure in the chamber. Itcan also be a spring on the axis where the support means turns around.By decreasing the diameter of the sealing portion it increases itslength. This is the case with an elastically deformable material whichis only a bit compressable, like e.g. rubber. Therefore the piston rodsticks out of this sealing means at the beginning of a stroke. If othermaterial for the sealing portion is chosen, its length can remainunchanged or can decrease by decreasing its diameter.

FIG. 4A shows a piston pump with a pressurizing chamber 21 with portionsof different transversal cross-section areas. The chamber has coolingribs 22 at the high-pressure side. The chamber can be (injection)moulded. The piston rod 23. The cap 24 guides the said piston rod. Thepiston 36 at the beginning and 36′ at the end of a pump stroke.

FIG. 4B shows the elastically deformable sealing portion 25 which isfastened to the piston rod 23 by means 26 (not drawn). A part 27 of thepiston rod 23 is sticking out of the sealing portion 25. Support portion28 is hanged up on ring 29 which is fastened to the piston rod 23.Support portion 28 can turn around axis 30. Loading portion 31 comprisesa spring which is fastened in a hole 32 onto the piston rod 23. Thesealing edge 38.

FIG. 4C shows that part 27 of piston rod 23 is almost covered by theelastically deformed sealing means 25′, which has now increased itslength and decreased its diameter. The sealing edge 38′.

FIG. 4D shows section A-A of FIG. 4B. The loading portion 31 is fastenedat one end in the hole 32 of the piston rod 23. The support portion 28and the ring 29. The support portion is stopped by a stop surface 33(not drawn). The support portion 28 is guided by the guiding means 34(not drawn).

FIG. 4E shows section B-B of FIG. 4C. The support means 28 and theloading means 31 are moved towards the piston rod 23. The rib 22.

FIG. 4F shows an alternative for the loading means 31. It comprisessprings 35 on each axis 30.

FIGS. 5A,B,C,D,E,F,G,H show details of the third embodiment. It is avariant of the first embodiment. The sealing portion comprises aflexible impervious membrane for gaseous and/or liquid media. Thismaterial can change its dimensions in three directions without folds.This sealing portion is mounted in an O-ring which seals to the wall ofthe chamber. The O-ring is loaded to the wall by a loading means, e.g. aspring in the circumference. The O-ring and spring are further supportedby a support means which can rotate around an axle fastened to thepiston rod. This support means can be loaded by a spring.

FIG. 5A shows a longitudinal cross-section of a piston pump analog tothat of FIG. 3A. The piston 49 at the beginning and 49′ at the end ofthe pump stroke.

FIG. 5B shows a piston means at the beginning of a stroke comprising asealing means 40: e.g. a stressed skin, that is fastened to a sealingmeans 41: e.g. an O-ring. This O-ring is loaded by a spring 42 which ispositioned on the circumference of the sealing means 41 and sealingmeans 40. The central axis 39 of the spring 42. The O-ring 41 and/orspring 42 is supported by support means 43 that can rotate on axis 44which is attached to the piston rod 45 and positioned perpendicular tothe central axis 19. It comprises of a certain amount of separatemembers 43′, loaded in compression during the (compression) pump stroke.These are positioned around the circumference of the sealing means 40,41and the loading means 42, which they support. The support means 43 canbe loaded by a spring 46. The angle β₁ between the wall of the chamber 2and the support means 43. The piston rod 45 is without an inlet or avalve. A supporting ring and/or loading ring in the form of a spring canbe mounted in the O-ring as an alternative for spring 42 (not drawn).The sealing edge 48.

FIG. 5C shows the piston means at the end of the stroke. The sealingmeans 40′, 41′ is thicker than at the beginning of a stroke: 40,41. Thespring 46′. The Angle β₂ between the wall 5 and the support means 43 atthe end of a stroke.

FIG. 5D shows section C-C of FIG. 5A with support means 43, axle 44 andbracket 47.

FIG. 5E shows section D-D from FIG. 5A.

FIG. 5F shows the two positions of the piston 118 of FIGS. 5G and 118′of FIG. 5H in a chamber.

FIG. 5G shows a piston which is made of a composite of materials. Itcomprises a skin 110 of elastic impervious material and fibers 111. Thefiber architecture results in the dome-form when it is under pressure.This form stabilizes the piston movement. As an alternative the sealingmeans can comprise a liner, fibers and a cover (not drawn). If the lineris not tight, an impervious skin could be added (not drawn). Allmaterials at the compressed side of the piston comply with the specificenvironmental demands of the chamber.

The skin is mounted in a sealing portion 112. Within the skin and thesealing portion a spring-force ring 113 can be mounted and which canelastically deform in its plane, and which enhances the loading of thering 114. The sealing edge 117.

FIG. 5H shows the piston of FIG. 5G at the end of a pump stroke. Thedome has been compressed into shape 115, if the is still fulloverpressure. Shape 110′ is a result if the overpressure is decreasede.g. after the media has been released.

FIGS. 6A,B,C show details of the fourth embodiment. The piston meanscomprises a rubber tube which has a reinforcement, e.g. in the form of atextile yard or cord wound around. The neutral angle between the tangentof the reinforcement winding and the centre line of the hose (=so-calledbraid angle) is mathematically calculated to be 54° 44′. A hose underinternal pressure will not change dimensions (length, diameter),assuming no elongation of the reinforcement. In this embodiment, thediameter of the piston means decreases in relation to the decreasingdiameter of the cross-section of the chamber at increasing pressures.The braid angle should be wider than neutral. The shape of the main partof the longitudinal cross-section of the pressurizing chamber isapproximately a cone shape due to the behaviour of the piston means. Atthe end of the pump stroke, when the compressed medium has been removedfrom the chamber, the piston means increases its diameter and its lengthis decreased. The diameter increase is no practical problem. The sealingforce from the piston to the wall of the pressurizing chamber ought toincrease by increasing pressure. This can e.g. be done by the choice ofa braid angle so that the piston diameter decreases a bit less than thedecrease in diameter of the transversal cross-section of the chamber.Therefore, the braid angle can also be chosen to be smaller than neutraland/or being neutral. In general, the choice of the braid angle dependsentirely on the design specification, and therefore the braid angle canbe wider and/or smaller and/or neutral. It is even possible that thebraid angle changes from place to place in the piston. Anotherpossibility is that in the same cross-section of the piston severalreinforcement layers are present with identical and/or different braidangles. Any type of reinforcement material and/or reinforcement patterncan be used. The place of the reinforcement layer(s) can be anywhere inthe longitudinal cross-section of the piston. The amount of liningsand/or covers can be more than one. It is also possible that a cover isabsent. The piston means can also comprise loading and supporting means,e.g. those showed earlier. In order to be able to adapt to largerchanges in the areas of cross-sections of the chamber a bit differentconstruction of the piston means is necessary. The cone comprises nowfibers which are under tension. These are coiled together in the top ofthe cone near the piston rod, and at the open side of the cone at thebottom of the piston rod. These can also be fastened to the piston roditself. The pattern of the fibers is designed e.g. so that these areunder higher tension the higher the pressure is in the chamber of pumpwhere the media is to be compressed. Other patterns are of coursepossible, just depending on the specification. They deform the skin ofthe cone, so that it adapt itself to the cross-section of the chamber.The fibers can lie loose on the liner or in loose in channels between aliner and a cover or they can be integrated on one of the two or inboth. It is necessary to have a loading means in order to obtain anappropriate sealing to the wall if there is no pressure under the coneyet. The loading member e.g. a spring force member in the form of aring, a plate etc. can be build in the skin e.g. by inserting in amoulding process. The suspension of the cone on the piston rod is betterthan of the foregoing embodiments because the piston will now be loadedby tension. Therefore being more in balance and less material is needed.The skin and the cover of the piston can be made of elasticallydeformable material which comply with the specific environmentalconditions, while the fibers can be elastically or stiff, made of anappropriate material,

FIG. 6A shows a longitudinal cross-section of a pump with chamber 60.The wall portions 61,62,63,64,65 are both cylindrical 61,65 andcone-shaped 62,63,64. Transitions 66,67,68,69 between the said portions.The piston 59 at the beginning and 59′ at the end of a pump stroke.

FIG. 6B shows piston means 50, a hose with a reinforcement 51. The hoseis fastened to the piston rod 6 by clamp 52 or similar. The piston 6 hasribs 56 and 57. Ribs 56 prevent the movement of the piston means 50relative to the piston rod 6 towards the cap 7, while ribs 57 preventthe movement of the piston means 50 relative to the piston rod 6 awayfrom the cap 7. Other configurations of the fitting are possible (notshown). On the outside of the hose, a protrusion 53 seals against thewall 61 of the chamber 60. Besides the reinforcement 51 the hosecomprises lining 55. As an example cover 54 is shown too. The shape ofthe longitudinal cross-section of the piston means is an example. Thesealing edge 58.

FIG. 6C shows the piston means at the end of the stroke, where thegaseous and/or liquid medium is under pressure.

The piston means may be designed in such a way that the diameter changeonly takes place via a radial change (not shown).

FIG. 6D shows the piston 189 of FIGS. 6E and 189′ of FIG. 6F at thebeginning and at the end respectively of a pump stroke in a chamber ofFIG. 6A.

FIG. 6E shows a piston means which has approximately the general shapeof a cone with top angle ½ε₁. It is shown when there is no overpressureat the side of the chamber. It is mounted in its top on a piston rod180. The cone is open at the pressurized side of the piston. The cover181 comprises a sealing portion shown as a protrusion 182 with a sealingedge 188 and an inserted spring force member 183, fibers 184 as supportmeans and a liner 185. The member 183 provides a loading to the cover,so that said protrusion 182 seals the wall of the chamber if there is nooverpressure at the side of the chamber. The fibers 184 can lie inchannels 186, and these are shown situated between the cover 181 and theliner 185. The liner 185 can be impervious—if not, a separate layer 209(not shown) at the pressurized side is mounted on the liner 185. Thefibers are mounted in the top 187 of the cone to the piston rod 180and/or to each other. The same is the case at the bottom end of thepiston rod 180.

FIG. 6F shows the piston means at the end of a stroke. The top angle isnow ½ε₂.

FIG. 7A,B,C,D,E show details of the fifth embodiment of the pump, with apiston which is constructed as another composite structure, comprising abasic material which is very elastic in all three dimensions, with avery high degree of relaxation. If it is not tight of itself, it can bemade tight with e.g. a flexible membrane on the pressurized side of thepiston means. The axial stiffness is accomplished by several integratedstiffeners, which in a transversal cross-section lie in a pattern, whichoptimally fills this section, while the in-between distance is reducedthe smaller the diameter of the transversal cross-sectional section is,which in most cases means the higher the pressure in the pressurizingchamber is. In the longitudinal section of the piston the stiffeners liein several angles between an axial direction and the direction of thesurface of the piston means. The higher the pressure rates are, the morethese angles are reduced and come near the axial direction. Nowtherefore the forces are being transferred to the support means, e.g. awasher, which is connected to the piston rod. The piston means can bemass-produced and is inexpensive. The stiffeners and, if necessary, thesealing means in the form of said flexible membrane, can be injectionmoulded together with said basic material in one operation. E.g. can thestiffeners be bonded together in the top, which makes handling easier.It is also possible to make the membrane by ‘burning’ it in said basicmaterial, during or after injection moulding. This is specificallyconvenient if the basic material is a thermoplast. The hinges shouldthan not be ‘burned’.

FIGS. 7F,G,H,I,J,K shows embodiments of the chamber and a sixthembodiment of the piston, fitting to this chamber. The sixth embodimentof the piston is a variant on the one of FIG. 7A,B,C,D,E. If the changeof the area of a transversal cross-section of the piston and/or thechamber between two positions in the direction of movement is continuousbut still so big that this results in leakages, it is advantageous tominimize the change of the other parameters of the cross-section. Thiscan be illustrated by using e.g. a circular cross-section (fixed shape):the circumference of a circle is πD, while the area of a circle is ¼πD²(D=diameter of the circle). That is to say, a reduction of D will onlygive a linear reduction of the circumference and a quadratic reductionof the area. It is even possible to also maintain the circumference andonly reduce the area. If also the shape is fixed e.g. of a circle thereis a certain minimum area. Advanced numeric calculations where the shapeis a parameter can be done by using the below mentioned Fourier Seriesexpansions. The transversal cross-section of the pressurizing chamberand/or the piston can have any form, and this can be defined by at leastone curve. The curve is closed and can approximately be defined by twounique modular parametrisation Fourier Series expansions, one for eachco-ordinate function:

${f(x)} = {\frac{c_{0}}{2} + {\sum\limits_{p = 1}^{\infty}{c_{p}{\cos ({px})}}} + {\sum\limits_{p = 1}^{\infty}{d_{p}{\sin ({px})}}}}$where$c_{p} = {\frac{2}{\pi}{\int_{0}^{\pi}{{f(x)}{\cos ({px})}\ {x}}}}$$d_{p} = {\frac{2}{\pi}{\int_{0}^{\pi}{{f(x)}{\sin ({px})}{x}}}}$0 ≤ x ≤ 2π, x ∈ _ p ≥ 0, p ∈ _

c_(p)=cos-weighted average values of f(x),d_(p)=sin-weighted average values of f(x),p=representing the order of trigonometrical fineness

FIGS. 7F,7K show examples of said curves by using a set of differentparameters in the following formulas. In these examples only twoparameters have been used. If more coefficients are used, it is possibleto find optimized curves which comply to other important demands as e.g.curved transitions of which the curves have a certain maximum radiiand/or e.g. a maximum for the tension in the sealing portion which undergiven premises may not exceed a certain maximum. All kinds of closedcurves can be described with this formula, e.g. a C-curve (seePCT/DK97/00223, FIG. 1A). One characteristic of these curves is thatwhen a line is drawn from the mathematical pole which lies in thesection plane it will intersect the curve at least one time.

The curves are symmetrical towards a line in the section plane, andcould also have been generated by the single Fourier Series expansionwhich follow. A piston or chamber will be more easy to produce when thecurve of the transversal cross-section is symmetric with reference to aline which lies in the section plane through the mathematical pole. Suchregular curves can approximately be defined by a single Fourier Seriesexpansion:

${f(x)} = {\frac{c_{0}}{2} + {\sum\limits_{p = 1}^{\infty}{c_{p}{\cos ({px})}}}}$where$c_{p} = {\frac{2}{\pi}{\int_{0}^{\pi}{{f(x)}{\cos ({px})}\ {x}}}}$0 ≤ x ≤ 2π, x ∈ _ p ≥ 0, p ∈ _

c_(p)=weighted average values of f(x),p=representing the order of trigonometrical fineness.

When a line is drawn from the mathematical pole it will always intersectthe curve only one time.

Specific formed sectors of the cross-section of the chamber and/or thepiston can approximately be defined by the following formula:

${f(x)} = {\frac{c_{0}}{2} + {\sum\limits_{p = 1}^{\infty}{c_{p}{\cos ( {3{px}} )}}}}$where${f(x)} = {r_{0} + {a \cdot \sqrt[{2m}]{{\sin^{2}( \frac{n}{2} )}x}}}$$c_{p} = {\frac{6}{\pi}{\int_{0}^{\frac{\pi}{3}}{{f(x)}{\cos ( {3{px}} )}{x}}}}$0 ≤ x ≤ 2π, x ∈ _ p ≥ 0, p ∈ _

c_(p)=weighted average values of f(x),p=representing the order of trigonometrical finenessand where this cross-section in polar co-ordinates approximately isrepresented by the following formula:

$r = {r_{0} + {a \cdot \sqrt[m]{{\sin ( {\frac{n}{2}\phi} )}}}}$

where

r₀≧0,

a≧0,

m≧0, mεR,

n≧0, nεR,

0≦_(—)≦2π,

and wherer=the limit of the “Petals” in the circular cross section of theactivating pin,r₀=the radius of the circular cross section around the axis of theactivating pin,a=the scale factor for the length of the “Petals”,r_(max)=r₀+am=the parameter for definition of the “Petal” widthn=the parameter for definition of the number of “petals”_=the angle which bounds the curve.The inlet is placed close to the end of the stroke due to the nature ofthe sealing portion of the piston means.

FIG. 7A shows a piston pump with a pressurizing chamber 70 in alongitudinal section with a cylindrical portion 71, a transition 72 to acontinuous concave curved portion 73, another transition 74 to an almostcylindrical portion 75. The piston means 76 and 76′ is shown at thebeginning respectively at the end of the pump stroke. At the end of theoutlet channel 77 a check valve 78 can be mounted (not shown).

FIG. 7B shows the piston means 76 comprising an elastic material 79which gives the longitudinal section of the piston at low pressures theform of approximately a cone. The material 79 functions also as aloading means. The bottom comprises a sealing means 80, which can befolded radially—this sealing means 80 is partially also working as aloading means. The main support means comprises of stiffeners 81 and 82,of which the stiffeners 81 mainly support the sealing edge 83 of thepiston means to the wall of the pressurizing chamber 70 while the otherstiffeners 82 transfer the load from the sealing means 80 and the basicmaterial 79 to the support means 84 e.g. a washer which is itselfsupported by the piston rod 6. The sealing means 80 is in this positionof the piston means 76 still a little bit folded, so that fold 85 willload the sealing edge 83 the more the higher the pressure will be in thechamber 70. Stiffeners 82 are joined together in the top by joint 86. Inthis position of the piston means 70 the stiffeners 81 and 82 havingangles between γ and δ with the central axis 19, where δ isapproximately parallel with the central axis 19 of the pressurizingchamber 70. The angle φ₁ between the surface of the piston 76 and thecentral axis 19.

FIG. 7C shows the piston means 76′ at the end of the pump stroke. Thesealing means 80 has been folded together, while the elastic material 79has been squeezed together, resulting in the stiffeners 81,82 aredirected approximately parallel with the central axis 19. The angle φ₂between the surface of the piston means 76′ and the central axis 19 ispositive, but almost zero. The sealing means 80′.

FIG. 7D shows a transversal cross-section E-E of the piston means 76,showing the basic elastic material 79, stiffeners 81 and 82, folds 87 ofthe sealing means 80. Piston rod 6.

FIG. 7E shows a transversal cross-section F-F of the piston means 76′,showing the basic elastic material 79, stiffeners 81 and 82, folds 87 ofthe sealing means 80. Clearly shown is that the elastic material 79 issqueezed together.

FIG. 7F shows a series of transversal cross-sections of a chamber wherethe area decreases in certain steps, while the circumference remainsconstant—these are defined by two unique modular parametrisation FourierSeries expansions, one for each co-ordinate function. At the top left isthe cross-section which is the start cross-section of said series. Theset of parameters used is shown at the bottom of the figure. This seriesshow decreasing area's of the transversal cross-section, but it is alsopossible to increase these area's by remaining the circumferenceconstant.

FIG. 7G shows a longitudinal cross-section of the chamber 162, of whichthe transversal cross-sectional area changes by remaining circumferencealong the central axis. The piston 163. The chamber has portions ofdifferent cross-sectional area's of its transversal cross-section ofwall sections 155,156,157,158. The transitions 159,160,161 between saidwall sections. Shown are cross-sections G-G, H-H and I-I. Cross-sectionG-G has a circelround cross-section, while cross-section H-H 152 haveapproximately an area between 90-70% of the one of cross-section G-G.

FIG. 7H shows transversal cross-section H-H 152 of FIG. 7G and in dottedlines as a comparison cross-section G-G 150. Cross-section H-H hasapproximately an area between 90-70% of that of cross-section G-G. Thetransition 151, which is made smooth. Also shown is the smallest part ofthe chamber, which has approximately 50% of the cross-sectional area ofcross-section G-G.

FIG. 7I shows a transversal cross-section I-I of FIG. 7G and in dottedlines as a comparison cross-section G-G. The cross-section I-I hasapproximately an area of 70% of that of cross-section G-G. Thetransition 153 is made smooth. Also shown is the smallest part of thechamber.

FIG. 7J shows a variant of the piston of FIG. 7A-C in cross-section H-Hfrom FIG. 7G. The piston is now made of elastic material which is alsoimpervious so that a separate sealing means is not necessary.

FIG. 7K shows a series of transversal cross-sections of a chamber wherethe area decreases in certain steps, while the circumference remainsconstant—these are defined by two unique modular parametrisation FourierSeries expansions, one for each co-ordinate function. At the top left isthe cross-section which is the start cross-section of said series. Theset of parameters used is shown at the bottom of the figure. This seriesshow decreasing area's of the transversal cross-section, but it is alsopossible to increase these area's by remaining the circumferenceconstant.

FIG. 8A,B,C show a seventh embodiment of the pump, with a piston meanswhich is constructed as another composite structure, comprising acompressable medium as e.g. a gaseous medium like for example air (alsois possible: only a non-compressible medium as e.g. a liquid medium likewater or a combination of compressable and a non-compressible medium)within a closed chamber which is constructed as e.g. a reinforced hose.It may be possible that the lining, reinforcement and cover at thepressurized side of the piston means is different from that of thenon-pressurized side—here the skin can be built up as a pre-formedshaped skin, holding this shape during the pump stroke. It is alsopossible that the skin is made of two or more parts, which itself arepre-formed shaped, one at the non-pressurized side of the piston means,the other on the pressurized side (please see FIG. 8B part X resp. partsY+Z). During the pump stroke the two parts hinge in each other (pleasesee FIG. 8B XY and ZZ). The adaptation of the sealing edge to thechamber in the transversal cross-section results in a change of thecross-section of the piston at its sealing edge, and this results in achange of the volume inside the piston. This gives a change in thepressure of the compressable medium and results in a changed sealingforce. Moreover, the compressable medium functions as a support portionas it transfers the load on the piston to the piston rod.

FIG. 8A shows a longitudinal section of the pressurizing chamber 90,comprising a continuos convex curve 91, with the piston 92 at thebeginning of the pump stroke, and 92′ at the end hereof. The highpressure part of the chamber 90 comprises an outlet channel 93 and aninlet channel 94 both with a check valve 95 and 96, respectively (notshown). For low pressure purposes the check valve 95 can be removed.

FIG. 8B shows piston 92 which is vulcanised directly on the piston rod97, comprising a compressible medium 103 within a lining 99, areinforcement 100 and a cover 101. Part X of the skin 99,100,101 ispre-shaped as it is with the parts Y and Z at the pressurized part ofthe piston means 92. A hinge XY is shown between part X and part Y ofthe skin. Part X has an average angle η₁ with the central axis 19 of thepressurized chamber 90. Part Y and Z are connected to each other andhave an in-between angle κ₁, which is chosen so that the forces will bedirected mainly to the piston rod. Angle λ between parts Y′ and Z′, andchosen so that the higher the force in the chamber, the more this partis perpendicular to the central axis. Hinge ZZ between the half of partZ. The sealing edge 102.

FIG. 8C shows the piston at the end of a stroke. Part X′ of the skin hasnow an angle η₂ with the central axis, while parts X′ and Y′ has anin-between angle κ₂, and an approximately unchanged angle λ between Y′and Z′. The angle between the halves of part Z is approximately zero.The sealing edge 102′ and compressed medium 103′.

FIG. 9A,B,C,D show details of a combination of a pressurizing chamberwith fixed dimensions and an eight embodiment of a piston which canchange its dimensions. The piston is an inflatable body which fills atransversal cross-section of the chamber. During the stroke it isconstantly changing its dimensions on and nearby the sealing edge. Thematerial is a composite of an elastically deformable liner and a supportmeans like e.g. fibers (e.g. glass, boron, carbon or aramid), fabric,filament or the like. Depending on the fiber architecture and the totalresulting loading on the piston—the piston is shown having a bitinternal overpressure—it can result in approximately the form of asphere or approximately an elleptical curve (‘rugby ball’-like form) orany shape in between, and also other shapes. A decrease of thetransversal cross-sectional area of e.g. the chamber causes a decreasein the size of the inflatable body in that direction and a 3-dimensionalreduction is possible due to the fiber architecture, which is based ojnthe ‘trellis-effect’ where fibers are shearing layerwise independentlyfrom each other. The cover is also made of an elastically deformablematerial, suitable for the specific environmental conditions in thechamber. If the liner nor the cover is impervious it is possible to usea separate bladder inside the body, as the body contains an gaseousand/or liquid media. The support means as e.g. fibers can only givestrength themselves if the pressure inside the body is bigger thanoutside, because these are than in tension. This pressure condition ispreferable to obtain a suitable sealing and life time. As the pressurein the chamber can change constantly, the pressure inside the bodyshould do the same and be a bit higher, or should always be higher atany point of the pump stroke by remaining constant. The last solutioncan only be used for low pressures as otherwise the piston would jam inthe chamber. For higher pressures in the chamber an arrangement isnecessary so that the internal pressure vary accordingly the variationsof the pressure in the chamber +should be a bit higher. This can beachieved by several different arrangements—loading regulatingmeans—which are based on the principles to change the volume and/orpressure of a medium inside the piston and/or to change the temperatureof the medium inside—other principles are possible too, as e.g. theright choice of the material of the skin of the piston, e.g. a specificrubber type, where it is E-module which defines the deformability, orthe right choice of the relative amount of the compressable part of thevolume inside the inflatable body, and its compressibility. Here annon-compressable medium is used inside the piston. By a change in thesize of the transversal cross-sectional area at the sealing edge thevolume of the piston changes, because the size of the piston in adirection of the movement is constant. This change causes thenon-compressable medium to flow to or from the a spring-force operatedpiston inside the hollow piston rod. It is also possible that saidspring-force operated piston is situated elsewhere. The combination ofthe pressure caused by the change of the volume of the piston and thechange in the pressure due to said spring-force results in a certainsealing force. The said spring-force works as a fine-tuning for thesealing force. An improved load regulation can be achieved by exchangingthe non-compressable medium by a certain combination of a compressableand a non-compressable medium, where the compressable medium works as aload regulating means. A further improvement is when said spring isexchanged by the operation force of the piston of the chamber, as itmakes the retraction of the piston easier, due to a lower sealing forceand a lower friction. A temperature raise of a medium inside the pistoncan be achieved when specifically a medium is chosen which can quicklybe warmed up.

FIG. 9A shows the longitudinal cross-section of the pressurizing chamberof FIG. 8A with the piston 146 of FIG. 9B at the beginning of a stroke,and of FIG. 9C at the end 146′ of a stroke.

FIG. 9B shows a piston 146 with an inflatable body having a wallcomprising fibers 130 which have a pattern, so that the inflated bodybecomes a sphere. Cover 131 and liner 132. An impervious bladder 133 isshown inside the sphere. The sphere is directly mounted on the pistonrod 120. It is locked at one end by a cap 121, and at the other end bycap 122. The hollow channel 125 of the piston rod 120 has a hole 123 inits side inside the sphere, so that the loading means being e.g. anincompressible medium 124 contained within the sphere can flow freely toand from the channel 125 of the piston rod 120. The other end of thechannel 125 is closed by a movable piston 126 which is loaded by aspring 127. The spring is mounted on a piston rod 128. The spring 127tunes the pressure in within the sphere and the sealing force. Thesealing surface 129 is approximately in a line contact with the of theadjacent wall of the chamber. The fibers are only shown schematically(in all the drawings of this application).

FIG. 9C shows the piston of FIG. 9B at the end of a stroke where thearea of the cross-section is smallest. The sphere has now a much biggersealing surface 134 which is uniform with the adjacent walls of thechamber. The piston 126 has moved in relation to its position shown inFIG. 9B, as the non-compressible medium 124′ has been squeezed out ofthe distorted sphere. In order to minimize the friction force it ispossible that the cover at the sealing surface has ribs (not shown) orcan have a low-frictional coating (as well as the wall of thechamber—not shown). As none of the caps 121 and 122 can move along thepiston rod 120, the trellis effect only can a part of the materialsurplus of the skin. The rest shows as a ‘shoulder’ 135 which reducesthe life time considerably, while it increases the friction as well. Thesealing edge 129′.

FIG. 9D shows an improved tuning of the sealing force, by having insidethe sphere an incompressible medium 136 and a compressible medium 137.The pressure of the media is regulated by a piston 138 with a sealingring 139 and a piston rod 140 which is directly connected to theoperating force. The piston 138 can slide in the cylinder 141 of thesphere. The stop 145 secures the sphere on the piston rod 140.

FIGS. 10A,B,C show an improved piston where the surplus of the skin bysmall cross-sections of the chamber can be released which means animproved life time and less friction. This method concerns the fact thata suspension of the piston on the piston rod can translate and/or rotateover the piston rod to a position farther from the side of the pistonwhere there is the biggest pressure in the chamber. A spring between themovable cap and a stop on the piston rod functions as another loadingregulating means.

FIG. 10A shows a longitudinal cross-section of the chamber 169 of a pumpaccording to the invention with two positions of the piston 168respectively 168′.

FIG. 10B shows a piston with an inflatable skin with a fibers 171 in atleast two layers with a fiber architecture which result in approximatelya sphere—ellipsoide, when inflated. Inside the piston can be animpervious layer 172, if the skin is not tight. The media is acombination of a compressible medium 173, e.g. air, and anincompressable medium 174, e.g. water. The skin 171 is mounted at theend of the piston rod in cap 175 which is fastened to the piston rod176. The other end of the skin is hinged fastened in a movable cap 177which can glide over the piston rod 176. The cap 177 is pressed towardsthe pressurized part of the chamber 169 by a spring 178 which issqueezed at the other end towards a washer 179 which is fastened to thepiston rod 176. The sealing edge 167.

FIG. 10C shows the piston of FIG. 10B at the end of the pump stroke. Thespring 178′ is compressed. The same is valid for the incompressablemedium 174′ and the compressible medium 173′. The skin 170′ is deformed,and has now a big sealing surface 167′.

FIGS. 11A,B,C show a piston which has at both of its ends in thedirection of movement on the piston rod a movable cap which takes thesurplus of material away. This is an improvement for a piston in aone-way piston pump, but specifically is it possible now to use thepiston in a dual operating pump where any stroke, also the retractionstroke, is a pump stroke. The movement of the skin during the operationis indirectly limited due to stops on the piston rod. These arepositioned so that the pressure of a medium in the chamber cannot stripthe piston from the piston rod.

FIG. 11A shows a longitudinal cross-section of the chamber with animproved piston 208 at the beginning and at the end (208′) of a stroke.

FIG. 11B shows a ninth embodiment of the piston 208. The skin of thesphere is comparable with the one of FIG. 10. An impervious layer 190inside is now tightly squeezed in the cap 191 in the top and the cap 192in the bottom. Details of said caps are not shown and all kinds ofassembling methods may be used. Both caps 191,192 can translate and/orrotate over the piston rod 195. This can be done by various methods ase.g. different types of bearings which are not shown. The cap 191 in thetop can only move upwards because of the existence of the stop 196inside the piston. The cap 192 in the bottom can only move downstairsbecause the stop 197 prevent a movement upwards. The ‘tuning’ of thesealing force comprises a combination of an incompressable medium 205and a compressable medium 206 inside the sphere, a spring-force operatedpiston 126 inside the piston rod 195. The media can freely flow throughthe wall 207 of the piston rod through holes 199, 200, 201. O-rings orthe like 202, 203 in said cap in the top and in said cap in the bottom,respectively seal the caps 191,192 to the piston rod. The cap 204,showed as a screwed assembly at the end of the piston rod 195 thighthenssaid piston rod. Comparable stops can be positioned elsewhere on thepiston rod, depending on the demanded movement of the skin.

FIG. 11C shows the piston of FIG. 11B at the end of a pump stroke. Thecap 191 in the top is moved over a distance x from the stop 196 whilethe bottom cap 192 is pressed against the stop 197. The compressablemedium 206′ and the non-compressable medium 205′.

FIGS. 12A,B,C show an improved piston in relation to the earlier one's.The improvements have to do with a better tuning of the sealing force bythe loading regulating means, a reduction of friction by a smallersealing contact surface, specifically by smaller cross-sectional area's.The improved tuning concerns the fact that the pressure inside thepiston now directly is influenced by the pressure in the chamber due toa pair of pistons on the same piston rod and which is by thatindependent of the existence of an operation force on the piston rod.This can be specifically advantageous during a stop in the pump stroke,if the operation force would change, e.g. increase, because the sealingforce remains constant and no loss of sealing occurs. At the end of apump stroke when the pressure in the chamber is decreased, theretraction will be more easy due to lower friction forces. In the caseof a dual operating pump, the loading regulating means can be influencedby both sides of the piston, e.g. by a double arrangement of this loadregulating means (not shown). The showed arrangement of the pistons iscomplying with a specification: e.g. an increase of the pressure in thechamber will give an increase of the pressure in the piston. Otherspecifications can result in other arrangements (please see on page27,28). The relation can be designed so that the increase can bedifferent than only a lineair relation. The construction is a pair ofpistons which are connected by a piston rod. The pistons can have anequal area, different size and/or a changing area.

Due to a specific fiber architecture and the total resulting loading—itis shown with a bit internal overpressure—the shape of the piston in alongitudinal cross-section is a rhomboid figure. Two of its corners inthis section work as a sealing surface, which gives a reduced contactarea by smaller transversals cross-sections of the chamber. The size ofthe contact surface can still be increased by the existence of a ribbedouter surface of the skin of the piston. The wall of the chamber and/orthe outside of the piston can have a coating as e.g. nylon or have beenmade of a low-friction material.

FIG. 12A shows a longitudinal cross-section of a piston chambercombination with a tenth embodiment of a piston 222 at the beginning andat the end (222′) of a stroke in a chamber 216.

FIG. 12B shows a piston of which the main construction is described inFIGS. 11B and 11C. The skin comprises at the outside ribs 210. The skinand the impervious layer 190 at the inside are squeezed at the topbetween an inner part 211 and an outer part 212, which are screwedtogether. At the bottom the similar construction exists with the innerpart 213 and the outer part 214. Inside the piston there is acompressable medium 215 and a non compressable medium 219. The pressureinside the piston is tuned by a piston arrangement which is directlyactivated by the pressure of the chamber 216. The piston 148 in thebottom which is connected to the pressurizing chamber 216 is mounted ona piston rod 217 while at the other side another piston 149 is mountedand which is connected to a medium of the piston 222. The piston rod 217is guided by a slide bearing 218—other bearing types can also be used(not shown). The pistons on both sides of the piston rod 217 can havedifferent diameters—it is even possible that the cylinder 221 these aremoving in, are exchanged by two chambers, which can be of a typeaccording this invention—by that, the piston and/or pistons are also ofa type according this invention. The sealing edge 220. The piston rod224. Distance d₁ between the piston 148 and orifice 223.

FIG. 12C shows the piston of FIG. 12A at the end of a stroke, whilethere is still high pressure in the chamber 216. Sealing edge 220′. Theload regulating means 148′ have a different distance from the orifice223 towards the chamber. Piston 148′ and 149′ are shown positioned at alarger distance than in FIG. 12B from the orifice 223: d₂.

FIG. 13A,B,C show the combination of a pump with a pressurizing chamberwith elastically deformable wall with different areas of the transversalcross sections and a piston with a fixed geometrical shape. Within ahousing as e.g. cylinder with fixed geometrical sizes an inflatablechamber is positioned which is inflatable by a medium (anon-compressable and/or a compressable medium). It is also possible thatsaid housing can be avoided. The inflatable wall comprising e.g. aliner-fiber-cover composite or also added an impervious skin. The angleof the sealing surface of the piston is a bit bigger than thecomparative angle of the wall of the chamber in relation to an axisparallel to the movement. This difference between said angles and thefact that the momentaneous deformations of the wall by the piston takesplace a bit delated (by having e.g. a viscose non-compressable medium inthe wall of the chamber and/or the right tuning of load regulatingmeans, which are similar to those which have been shown for the pistons)provides a sealing edge, of which its distance to the central axis of tochamber during the movement between two piston and/or chamber positionscan vary. This provides a cross-sectional area changes during a stroke,and by that, a designable operation force. The cross-section of thepiston in the direction of the movement however can also be equal, orwith a negative angle in relation to the angle of the wall of thechamber—in these cases the ‘nose’ of the piston ought to be rounded of.In the last mentioned cases it is more difficult to provide a changingcross-sectional area, and by that, a designable operation force. Thewall of the chamber can be equiped with all the already showed loadingregulating means the one showed on FIG. 12B, and if necessary with theshape regulating means.

FIG. 13A shows piston 230 at four positions of the piston in a chamber231. Around an inflatable wall a housing 234 with fixed geometricalsizes. Within said wall 234 a compressable medium 232 and anon-compressable medium 233. There can be a valve arrangement forinflation of the wall (not shown). The shape of the piston at thenon-pressurized side is only an example to show the principle of thesealing edge.

FIG. 13B shows the piston after the beginning of a stroke. The distancefrom the sealing edge 235 and the central axis 236 is z₁. The angle ζbetween the piston sealing edge 235 and the central axis 236 of thechamber. The angle ζ between the wall of the chamber and the centralaxis 236. The angle v is shown smaller than the angle ζ. The sealingedge 235 arranges that the angle v becomes as big as the angle ζ.

Other embodiments of the piston are not shown.

FIG. 13C shows the piston during a stroke. The distance from the sealingedge 235 and the central axis 236 is z₂—this distance is smaller thanz₁.

FIG. 13D shows the piston almost at the end of stroke. The distance fromthe sealing edge 235 and the central axis 236 is z₃—this distance issmaller than z₂.

FIG. 14 shows a combination of a wall of the chamber and the pistonwhich have changeable geometrical shapes, which adapt to each otherduring the pump stroke, enabling a continuous sealing. Shown is thechamber of FIG. 13A now with only a non-compressable medium 237 andpiston 222 at the beginning of a stroke, while the piston 222″ is shownjust before the end of a stroke. Also all other embodiments of thepiston which can change dimensions can be used here too.

If the piston pump is a handpump for tire inflation purposes it can havean integrated connector according to those disclosed in PCT/DK96/00055(including the US Continuation in Part of 18 Apr. 1997), PCT/DK97/00223and/or PCT/DK98/00507. The connectors can have an integrated pressuregauge of any type. In a piston pump according to the invention used ase.g. a floor pump or ‘carpump’ for inflation purposes a pressure gaugearrangement can be integrated in this pump.

In the above inflatable pistons with a skin with a fiber architecturehas been shown where there is overpressure in the piston in relation tothe pressure in the chamber. It is however also possible to have anequal or lower pressure in the piston than in the chamber—the fibers arethan under pressure instead of under tension. The resulting shape can bedifferent than those which are shown in the drawings. In that case theloading regulating means have to be tuned differently, and the fibershave to be supported. The load regulating means showed in e.g. FIG. 9Dor 12B should than be constructed so that the movement of the piston ofthe means gives a suction in the piston, e.g. by an elongation of thepiston rod, so that the pistons are now at the other side of the holesin the piston rod. The change in the form of the piston is thandifferently and a collapse can be obtained. This will reduce thelife-time.

Through these embodiments, reliable and inexpensive pumps optimized formanual operation, e.g. universal bike pumps to be operated by women andteenagers, can be obtained. The shape of the walls of the pressurizingchamber (longitudinal and/or transversal cross-section) and/or pistonmeans of the pumps shown are examples and may be changed depending onthe pump design specification. The invention can also be used with allkinds of pumps, e.g. multiple-stage piston pumps as well as withdual-function pumps, piston pumps driven by a motor, pumps where e.g.only the chamber or piston is moving as well as types where both thechamber and the piston are moving simultaneously. Any kind of medium canbe pumped in the piston pumps. Those pumps can be used for all kinds ofapplications, e.g. in pneumatic and/or hydraulic applications. And, theinvention is also applicable for pumps which are not manually operated.The reduction of the applied force means a substantial reduction ofinvestments for equipment and a substantial reduction of energy duringoperation. The chambers can be made e.g. by injection moulding, fromdrawn tubes etc.

The preferred embodiments of the combination of a chamber and a pistonhas been described as examples to be used in piston pumps. This howevershould not limit the coverage of this invention to the said application,as it is mainly the valve arrangement of the chamber besides the factwhich item or medium is initiating the movement, which is descisive forthe type of application: pump, actuator, shock absorber or motor. In apiston pump a medium is sucked into a chamber which is thereafter closedby a valve arrangement. The medium is compressed by the movement of thechamber and/or the piston and a valve releases this compressed mediumfrom the chamber. In an actuator a medium is pressed into a chamber by avalve arrangement and the piston and/or the chamber is moving,initiating the movement of an attached devise. In shock absorbers thechamber can be completely closed, wherein the chamber a compressablemedium can be compressed by the movement of the chamber and/or thepiston. In the case a non-compressable medium is inside the chamber,e.g. the piston can be equipped by several small channels which give adynamic friction, so that the movement is slowed down.

Further the invention can also be used in propulsion applications wherea medium is used to move a piston and/or a chamber, which can turnaround an axis as e.g. in a motor. The principles according thisinvention are applicable on all above mentioned applications.

The principles of the invention can also be used in other pneumaticand/or hydraulic applications than the above mentioned piston pumps.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the invention.Those skilled in the art will readily recognize various modifications,changes, and combinations of elements which may be made to the presentinvention without strictly following the exemplary embodiments andapplications illustrated and described herein, and without departingfrom the true spirit and scope of the present invention.

1. A piston-chamber combination comprising an elongate chamber which isbounded by an inner chamber wall and comprising a piston in said chamberto be sealingly movable relative to said chamber at least between firstand second longitudinal positions of said chamber, said chamber havingcross-sections of different cross-sectional areas at the first andsecond longitudinal positions of said chamber and at least substantiallycontinuously differing cross-sectional areas at intermediatelongitudinal positions between the first and second longitudinalpositions thereof, the cross-sectional area at the first longitudinalposition being larger than the cross-sectional area at the secondlongitudinal position, said piston being designed to adapt itself andsaid sealing means to said different cross-sectional areas of saidchamber during the relative movements of said piston means from thefirst longitudinal position through said intermediate longitudinalpositions to the second longitudinal position of said chamber, whereinthe piston comprises: a plurality of at least substantially stiffsupport members rotatably fastened to a common member, elasticallydeformable means, supported by the supporting members, for sealingagainst an inner wall of the chamber the support members being rotatablebetween 10° and 40° relative to the longitudinal axis.
 2. A combinationaccording to claim 1, wherein the support members are rotatable so as tobe at least approximately parallel to the longitudinal axis.
 3. Acombination according to claim 1 or 2, wherein the common member isattached to a handle for use by an operator, and wherein the supportmembers extend, in the chamber, in a direction relatively away from thehandle.
 4. A combination according to claim 1 or 2, further comprisingmeans for biasing the support members against an inner wall of thechamber
 5. A combination according to claim 1, wherein thecross-sections of the different cross-sectional areas have differentcross-sectional shapes, the change in cross-sectional shape of thechamber being at least substantially continuous between the first andsecond longitudinal positions of the chamber, wherein the piston isfurther designed to adapt itself and the sealing means to the differentcross-sectional shapes.
 6. A combination according to claim 5, whereinthe cross-sectional shape of the chamber at the first longitudinalposition thereof is at least substantially circular and wherein thecross-sectional shape of the chamber at the second longitudinal positionthereof is elongate, such as oval, having a first dimension being atleast 2, such as at least 3, preferably at least 4 times a dimension atan angle to the first dimension.
 7. A combination according to claim 5or 6, wherein the cross-sectional shape of the chamber at the firstlongitudinal position thereof is at least substantially circular andwherein the cross-sectional shape of the chamber at the secondlongitudinal position thereof comprises two or more at leastsubstantially elongate, such as lobe-shaped, parts.
 8. A combinationaccording to any of claims 5 to 7, wherein a first circumferentiallength of the cross-sectional shape of the cylinder at the firstlongitudinal position thereof amounts to 80-120%, such as 85-115%,preferably 90-110, such as 95-105, preferably 98-102%, of a secondcircumferential length of the cross-sectional shape of the chamber atthe second longitudinal position thereof.
 9. A combination according toclaim 8, wherein the first and second circumferential lengths are atleast substantially identical.
 10. A pump for pumping a fluid, the pumpcomprising: a combination according to claims 1 and 5, means forengaging the piston means from a position outside the chamber, a fluidentrance connected to the chamber and comprising a valve means, and afluid exit connected to the chamber.
 11. A pump according to claim 10,wherein the engaging means have an outer position where the piston meansis at the first longitudinal position of the chamber, and an innerposition where the piston means is at the second longitudinal positionof the chamber.
 12. A pump according to claim 10, wherein the engagingmeans have an outer position where the piston means is at the secondlongitudinal position of the chamber, and an inner position where thepiston means is at the first longitudinal position of the chamber.
 13. Ashock absorber comprising: a combination according to claim 1 or 5,means for engaging the piston means from a position outside the chamber,wherein the engaging means have an outer position where the piston meansis at the first longitudinal position of the chamber, and an innerposition where the piston means is at the second longitudinal position.14. A shock absorber according to claim 13, further comprising a fluidentrance connected to the chamber and comprising a valve means.
 15. Ashock absorber according to claim 13 or 14 further comprising a fluidexit connected to the chamber and comprising a valve means.
 16. A shockabsorber according to any of claims 13 to 15, wherein the chamber andthe piston means form an at least substantially sealed cavity comprisinga fluid, the fluid being compressed when the piston means moves from thefirst to the second longitudinal positions of the chamber.
 17. A shockabsorber according to any of claims 13 to 15, further comprising meansfor biasing the piston means toward the first longitudinal position ofthe chamber.
 18. An actuator comprising: a combination according to anyof claim 1 or 5, means for engaging the piston means from a positionoutside the chamber, means for introducing fluid into the chamber inorder to displace the piston means between the first and the secondlongitudinal positions of the chamber.
 19. An actuator according toclaim 18, further comprising a fluid entrance connected to the chamberand comprising a valve means.
 20. An actuator according to claim 18 or19, further comprising a fluid exit connected to the chamber andcomprising a valve means.
 21. An actuator according to any of claims 18to 20, further comprising means for biasing the piston means toward thefirst or second longitudinal position of the chamber.
 22. An actuatoraccording to any of claims 18 to 21, wherein the introducing meanscomprise means for introducing pressurised fluid into the chamber. 23.An actuator according to any of claims 18 to 21, wherein the introducingmeans are adapted to introduce a combustible fluid, such as gasoline ordiesel, into the chamber, and wherein the actuator further comprisesmeans for combusting the combustible fluid.
 24. An actuator according toany of claims 18 to 21, further comprising a crank adapted to translatethe translation of the piston means into a rotation of the crank.